Understand what the browser needs
A CNAME record makes one DNS name an alias of another. For example, www.example.com might point to site.example.net, which then points to a name with A or AAAA address records. A DNS resolver follows those links to find an address the browser can use. A chain is not necessarily a problem, but every link must lead somewhere useful.
A broken chain ends at a name that does not exist, lacks the address record needed for the lookup, or cannot be resolved because of a DNS error. A loop sends the resolver back to a name it has already visited. Either problem can keep a site from loading, although the exact error shown depends on the resolver and browser. These are DNS problems, not HTTP redirects: a redirect happens after a browser has reached a web server.
Trace the chain one name at a time
Start with the exact hostname that fails, including a prefix such as www. Check both address types, since a name may have an IPv4 address, an IPv6 address, or both. From a terminal with dig installed, try dig www.example.com A and dig www.example.com AAAA. Look at the answer and any CNAME shown. You can then query each target by name to see where it leads. The example names here are placeholders; substitute the hostname you are authorized to troubleshoot.
Write the path down as you go: requested name → first CNAME target → next target → address record. Querying dig www.example.com CNAME can make an alias easier to spot, while querying A and AAAA helps show whether the full path produces an address. If a lookup returns no answer, check the response status as well as the answer section. NXDOMAIN indicates that a name does not exist in the view you queried; an empty answer alone does not prove the chain is broken. SERVFAIL points to a resolution failure that may need separate investigation.
Compare results from your usual resolver with another resolver if available, and check the relevant authoritative DNS records in your DNS provider’s control panel. Cached answers can differ temporarily after an edit. Keep the record names, targets, response statuses and times of your tests, but do not share account credentials or provider access tokens in a troubleshooting post.
Recognize a missing link or a loop
A missing link might look like www.example.com pointing to app.example.net when app.example.net has been removed. First confirm that the CNAME target is spelled correctly, including every label in the name. Then check whether the target exists and ultimately supplies an appropriate address. If the target belongs to a hosting provider, verify the hostname against the provider’s configuration for your site rather than guessing at a replacement.
A loop is easier to see when the path is written out. Suppose www.example.com points to site.example.net, and site.example.net points back to www.example.com. Neither name leads to an address. A longer chain can hide the same problem across several zones. If a name repeats before you reach an A or AAAA record, identify which CNAME should instead point toward the intended destination.
Also check for mistakes beside the chain. A CNAME should not be configured alongside other ordinary DNS records at the same name. If the failing hostname also needs records such as MX or TXT, review the design before changing it. The zone apex—the bare domain without a prefix—normally cannot be a standard CNAME, although some DNS providers offer alias or flattening features that behave differently in their control panels.
Fix the intended record, then verify the result
Before editing DNS, determine which organization controls the incorrect link. You can fix a CNAME in a zone you manage; you usually cannot repair a target in someone else’s zone. For a third-party target, confirm that you copied the assigned hostname correctly and contact the provider if its published target does not resolve. Avoid making several speculative changes at once, because that makes the cause harder to identify.
After a correction, query the original hostname again for A and AAAA, and follow the CNAME path to confirm it now ends at an address. Check from the authoritative records and through a recursive resolver if you can. Cached answers, including cached failures, may remain until their applicable time-to-live periods expire, so an immediate mismatch does not always mean the edit failed.
Finally, test the website itself. If DNS reaches an address but the page still fails, shift your attention to connectivity, server configuration, TLS certificates or HTTP redirects. A complete CNAME chain answers the DNS question; it does not, by itself, guarantee that the website is ready to serve visitors.
